Fibrinogen FSR 'pivotal' to impact of exercise on childhood hypercoagulability

14 August 2008

MedWire News: The fibrinogen fractional synthesis rate (FSR) is key to the correction of a hypercoaguable state in obese children through exercise, US research suggests.

"The magnitude of reduction in FSR and the congruent reductions in FSR and concentration of fibrinogen speak to the pivotal role of FSR in decreasing the obesity-related hyperfibrinogenemia in children," Prabhakaran Balagopal (Nemours Children's Clinic, Jacksonville, Florida) and colleagues report in the Journal of Thrombosis and Haemostasis.

"Although fibrinolysis remained unaltered after the intervention, the extent of reductions in FSR of fibrinogen in the context of matching reductions in concentrations of fibrinogen and D-dimer imply that intervention resulted in an overall improvement in the prothrombotic state associated with obesity in children," they say.

The team determined the impact of a physical activity-based intervention, consisting of 45-60 minutes of aerobic exercise three times a week for 3 months on FSR and other markers of fibrinolytic potential in obese children (body mass index [BMI]>95 percentile for age and gender).

Seven obese patients, aged 15-17 years, were assigned to the intervention while eight age- and maturity-matched obese patients were given general lifestyle information.

At baseline, the obese patients had significantly greater levels of fibrinogen FSR than six lean control teenagers, as well as higher levels of plasminogen activator inhibitor (PAI)-1, tissue plasminogen activator (tPA), and D-dimer.

At the 3-month follow-up, patients had experienced only small changes in their BMI but a significant decrease was detected in fibrinogen FSR in intervention patients compared with controls.

There was a correlation between changes in FSR and fibrinogen concentration, and the reduction in the FSR "almost entirely accounted for the reduction in its concentration," the researchers note.

The exercise intervention patients also experienced a decrease in D-dimer levels not seen in the controls, but neither group had a change in PAI-1 or tPA levels.

"The question of whether the reduction in FSR of fibrinogen after physical activity in the present study is unique to obese children with an advantage over adults and/or the elderly remains unanswered," Balagopal et al write.

"Indeed a potential difference in the regulation of fibrinogen levels in childhood versus senescence and the effect of different interventions on the FSR of fibrinogen may be consequential in developing therapies for thrombosis in a variety of conditions."

J Thromb Haemost 2008; 6: 1296-1303